The present invention relates to a device for humidifying and ionizing air, particularly for domestic use.
As is known, various types of air humidifiers for domestic use are commercially available; one of them is the ultrasonic humidifier. This humidifier exploits the natural phenomenon of forced evaporation of water when it is forced to resonate at a certain frequency (approximately 1.7 MHz). In known devices, the water is in contact with an ultrasound source, usually a piezoelectric transducer driven by an electronic oscillator, so as to make the transducer vibrate at the intended frequency. When this frequency is brought to approximately 1.7 MHz, the transducer causes the water molecules to vibrate, increasing their kinetic energy and allowing them to pass beyond the surface of the water, thus creating an evaporation effect.
A drawback of known humidifiers, and of electronic devices in general, is that, during the operation of the transducer driven by the oscillator, said oscillator is heated due to its internal resistance. To allow normal operation of the oscillator (and of the other electronic components) and prevent damage thereof due to excessive temperature, the oscillator has a heat sink made of metal (usually aluminum). Since heat dissipation is proportional to the surface of the heat sink, the device requires a rather large heat sink, thus increasing the bulk of the humidifier. The same drawback is found in the electronic circuits of known ionizers.
Furthermore, as is known, ionizers of different kinds are available on the household-appliance market. Ionizers use another natural phenomenon, which is the ionization of air molecules when they are in contact with an electrode which has a high negative-polarity electrical potential (5000-6000 V). The amount of air ionization is a function of the potential of the electrode. If the potential exceeds a certain value, one obtains the unwanted effect (Corona effect) of producing ozone. Ozone production is undesirable because less ions are produced if ozone is formed and because ozone has recently been considered harmful to the health.
The efficiency of ionization, i.e. the number of ions produced in a given time interval, is lower in a humid environment, since the water molecules are ionized, causing a drop of voltage at the ionization electrode due to the conductance of the water vapor in the air. Furthermore, very humid air is more suitable for ozone forming due to the Corona effect, which produces sparks.
Thus, if the user wishes to have a humidifier and an ionizer in the same room, he must keep them far apart in order to avoid negative ozone-forming effects and produce a sufficient number of ions. As an alternative, the user can keep the two appliances close to each other and operate them alternately.
Furthermore, this situation entails the need to have two clearly distinct appliances with a power outlet for each one.